Optical distance measuring system and light ranging method

Abstract

An optical distance measuring system includes a multi-wavelength pulse light source configured to generate a plurality of light pulses of different wavelengths and repeat a cycle in which the light pulse is generated while sequentially changing the wavelength thereof; a scan device configured to scan the light pulses; a wavelength-selectable light receiver configured to receive reflection light of the plurality of light pulses of difference wavelengths from a target and generate a light receiving signal that corresponds to each of the plurality of different wavelengths; and a processor configured to detect time from the generation of each of the plurality of light pulses of different wavelengths in the multi-wavelength pulse light source to the generation of the light receiving signal of a corresponding wavelength which is generated in predetermined time and calculate a distance to the target in a scanning direction from the detected time.

What is claimed is: 
     
         1 . An optical distance measuring system comprising:
 a multi-wavelength pulse light source configured to generate a plurality of light pulses of different wavelengths and repeat a cycle in which the light pulse is generated while sequentially changing the wavelength thereof;   a scan device configured to scan the light pulses;   a wavelength-selectable light receiver configured to receive reflection light of the plurality of light pulses of difference wavelengths from a target and generate a light receiving signal that corresponds to each of the plurality of different wavelengths; and   a processor configured to   detect time from the generation of each of the plurality of light pulses of different wavelengths in the multi-wavelength pulse light source to the generation of the light receiving signal of a corresponding wavelength which is generated in predetermined time and calculate a distance to the target in a scanning direction from the detected time.   
     
     
         2 . The optical distance measuring system according to  claim 1 ,
 wherein the multi-wavelength pulse light source includes a wavelength variable laser.   
     
     
         3 . The optical distance measuring system according to  claim 1 ,
 wherein the wavelength-selectable light receiver includes   a plurality of light receiving elements, and   a plurality of thin film filters disposed in incident parts of the plurality of light receiving elements and configured to selectively pass the plurality of different wavelengths.   
     
     
         4 . The optical distance measuring system according to  claim 1 ,
 wherein the scan device is a microelectromechanical Systems scanner.   
     
     
         5 . The optical distance measuring system according to  claim 1 ,
 wherein when the maximum measurable distance of the optical distance measuring system is Dmax and the multi-wavelength pulse light source generates light pulses of different wavelengths of N types, the multi-wavelength pulse light source generates the light pulses at certain time intervals of 2*Dmax/(N*c) or more and 2*Dmax/c or less, where c is the velocity of light.   
     
     
         6 . A light ranging method comprising:
 repeating a cycle in which light pulses of difference wavelengths are sequentially generated;   scanning the light pulses;   receiving reflection light of the light pulses from a target and generating light receiving signals corresponding to the different wavelengths;   detecting time from the generation of each of the light pulses to the generation of the light receiving signal of a corresponding wavelength in predetermined time; and   calculating a distance to the target in a scanning direction from detected time.